Catalyst Biosciences, Inc. (NASDAQ:CBIO) , a company that is developing improved treatments for hemophilia, expects to update investors on December 18, 2018 regarding its review of the neutralizing antibodies (nAB) observed in Cohort 6 of a phase I/II study earlier this year.
The update by Catalyst should shed more light on the disappointment of the phase I/II results announced six months ago. Catalyst shares declined approximately 60% after the study results were announced.
Catalyst shares traded as high as $37 per share in February before declining to a 52-week low of $8.90 per share in November 2018. The company’s shares rose 6% on December 3 after it released positive data for a different hemophilia drug, activated marzeptacog alfa (MarzAA), on December 1.
Hemophilia patients lack the ability to produce blood-clotting factors, principally Factor VIII in Hemophilia A or Factor IX (FIX) in Hemophilia B. Catalyst’s phase I/II study evaluated its FIX variant dalcinonacog alfa (DalcA) in severe Hemophilia B patients.
In two patients in Cohort 6, nABs were observed after administration, indicating the patients’ were reacting to the infusion of DalcA, treating it as a foreign invader even though DalcA is designed to mimic FIX.
Catalyst has since discovered the two patients with the nAB reactions were cousins. The company conducted a comprehensive review of the two Cohort 6 patients since the study results were announced on June 18, 2018.
The update by Catalyst on December 18 may inform the market if the reactions by the two patients were an anomaly. Catalyst could have identified a biomarker in the two patients which would trigger the production of nABs. If so, development of DalcA could proceed with the confidence the drug would work in patients not displaying that biomarker.
In the first five cohorts of the Catalyst phase I/II study, no nABs were observed in any patients, including two different patients in Cohort 6 who had also participated in Cohort 5. At the time of the trial, Catalyst noted patients in Cohort 6 were able to maintain Factor IX levels of more than 30% which is at the upper end of mild hemophilia and higher than currently approved extended half-life (EHL) intravenous Factor IXs.
FVIII deficiency (Hemophilia A) accounts for 80% of such cases and affects 1:5m000 male births, while FIX deficiency, or hemophilia B (HB), affects 1:30,000 male births worldwide.